Will a Furnace Work with a Cracked Heat Exchanger?

The natural gas furnace has everything most homes need in a heating system. It heats the whole home from a central location, it connects to the gas line available for most homes to access, and it does not cost an arm and a leg to run. Furthermore, today’s gas furnaces are safer than they have ever been before.

However, there is still a small risk when running any natural gas appliance of the dangerous byproducts of combustion leaking into a home. Perhaps the biggest risk with a furnace is a cracked heat exchanger. This is the component that allows heat to transfer to the air moving through your home, so shouldn’t the furnace shut off if the heat exchanger is cracked? Is this really something to worry about?

The Dangers of Carbon Monoxide

Carbon monoxide is a toxic gas. Naturally, it is produced as a byproduct during the combustion process that burns fuel to ignite a flame. It should vent out through the heat exchanger to a flue leading outside of the home, if everything is in good order. But it’s possible for carbon monoxide to leak out into the home.

CO has no detectable odor or color, meaning it can be incredibly difficult to detect. Unfortunately, some people don’t notice a carbon monoxide leak until people in the house start to get sick, and the risk of death is extremely serious.

The Risk of a Cracked Heat Exchanger

But is a cracked heat exchanger really that big of a concern? Certainly, manufacturers know the safety risk and build the heat exchanger to be as stable as possible. However, there are circumstances in which a cracked heat exchanger is more likely.

One such scenario is when you have inexperienced people service or install your furnace, which may cause accidental breakage to this component and others. The heat exchanger may also leak due to delayed ignition, which can create a near-explosion that can rattle the heater components and crack the heat exchanger.

Will the Furnace Shut Off?

Modern-day furnaces have many safety switches that help to shut off the system or close off gas valves in a potentially dangerous situation. For example, the flame sensor shuts off the valves when there is no flame detected at the burners to avoid a gas leak.

Detecting a cracked furnace heat exchanger, though, is a little different. There is no way for a furnace to “sense” that it has cracked. However, there is one safety switch present only on some models of furnace. If there is a fan helping to move byproducts through the flue, a safety switch may shut off the system if there is not enough air pressure.

Taking the Proper Precautions

What’s most important is that you take the proper precautions to keep your family safe.

Replace a furnace that is a couple of decades old and may be dangerous.

Schedule routine maintenance and inspections for your furnace each year.

Install carbon monoxide detectors throughout the home and test them once a month.